Starch comprises two polysaccharides: amylose and amylopectin. Amylose is a generally linear polymer that comprises glucose units connected by alpha 1-4 glycosidic linkages. Amylopectin is a branched polymer in which many of the glucose units are connected by alpha 1-4 glycosidic linkages, but some are connected by alpha 1-6 glycosidic linkages.
Alpha-amylase is an enzyme that is present in the human body and which hydrolyzes alpha 1-4 linkages in starch, thus leading to digestion of the starch. In certain situations it is desirable to produce starch that resists hydrolysis by alpha-amylase, for example to decrease the caloric content of the starch, or to increase its dietary fiber content. However, attempts to produce such starch in the past have suffered from one or more problems, such as high cost.
Amylase-resistant starch is usually produced from high-amylose starch, which is often expensive. There is a need for improved processes for producing starch with a high content of amylose that is suitable for production of alpha-amylase resistant starch.